Can i edit the workflow Start Form without Nintex forms?

In my company we are running Nintex Workflows 2013 on Sharepoint. I need to modify the Start Form of one of the workflows that we currently have to include a couple of more options that will be used later in the workflow. When in the workflow settings the "Edit Start Form" is grayed out. I believe that the reason is because we dont have Nintex Form package as part of our license. My questions are:

a) Is it the case that if you dont have Nintex Forms installed, the button "Edit Start Form" would be grayed?

b) Is there an alternative of creating/modifying a Start Form without the need of Nintex Forms?